• facebook
  • twitter
  • whatsapp
  • telegram

Organic Compounds Containing Nitrogen

    Proteins, vitamins, hormones, dyes, drugs, polymers are amines. Adrenaline, ephedrine are used to increase blood pressure are secondary amines. Antihistamine,  Bendryl, Anaesthetic Novocian (used in dentistry) are tertiary amines, surfactants are quaternary amines. Diazonium salts are ued in the preparation of dyes. Amines are the derivatives of ammonia. Replacement of one 'H' atom of ammonia with alkyl or aryl group (RNH2) is called as primary amine, two 'H' atoms is called secondary amine (R2NH), three 'H' atoms is called tertiary amine (R3N). Amines behave as Lewis bases
Preparation of amines:
By reduction of alkyl or aryl Nitro compounds with H2 & Pd or with Fe &  HCl.

By ammonolysis of alkyl halides.

By reduction of Nitriles (-CN) with LiAlH4

By Gabriel Phthalimide synthesis:
Phthalimide on reaction with ethanolic KOH followed by heating with alkylhalide and hydrolysis gives aliphatic (aromatic amines can not be prepared) primary amine.


By Hoffmann bromide degradation:
       By treating alkyl or aryl amide with Br2 in aqueous or ethanolic solution, primary amine is formed.
       C3 H7 CONH2 + Br2 + 4 NaOH C3H7NH2 + Na2CO3 + 2 H2O + 2 NaBr


Chemical Reactions
Basic character:
       Basic nature of aqueous alkylamines depend on +I or -I steric, H - bonding, solvation effects. Alkyl amines are stronger bases than NH3. Electron releasing groups like -CH3, -OCH3 will increase basic character & electron withdrawing groups like -NO2, -X-COOH, -SO3H will decrease basic character in aromatic amines.
Order of basic character in gaseous state:
      NH3< CH3NH2< (CH3)2 NH < (CH3)3 N
In aqueous state:
     NH3< (CH3)3 N < CH3NH2< (CH3)2 NH
     NH3< C2H5NH2< (C2H5)3 N < (C2H5)2 NH
     C6H5NH2< NH3< C2H5NH2


Alkylation:
     Primary Amines on alkylation with alkyl halides give 2°, 3° amines and  quaternary salts.
Acylation:
    The reaction between aliphatic & aromatic primary & secondary amines and acid chlorides, esters and anhydrides by nucleophilic substitution reaction is called acylation.

Benzoylation of amines takes place with benzoyl chloride (C6H5COCl)
Carbyl amine reaction:
      A dirty smelling compound carbyl amine (Isocyanide) is formed when  aliphatic or aromatic primary amine is heated with Chloroform and Ethanolic KOH.

Reaction with HNO2:
      1° aliphatic aimes react with HNO2 to form unstable aliphatic diazonium salt,  which on hydrolysis gives alcohol.

Reaction with Benzene sulphonyl chloride (Hinsberg's reagent):
1° Amine gives alkali soluble N-ethylbenzene sulphonamide with C6H5SO2Cl.

2° Amine gives alkali insoluble N, N - diethylbenzene sulphonamide with C6H5SO2Cl.


 3o Amine do not react with C6H5SO2Cl.


Electrophilic Substitution Reactions
Bromination: Aniline reacts with bromine water at room temperature gives a white ppt. of 2, 4, 6 tribromoaniline.


* p - bromoaniline can be prepared by a acetylation of aniline followed by hydrolysis.

Nitration:
      Direct nitration of aniline with nitration mixture (Conc. HNO3 + Conc. H2SO4)  at 288 K temperature gives 51% para, 47% meta and 2% ortho nitro anilines.  Aniline on acetylation gives para Nitroaniline.

 

Sulphonation:
      Aniline on sulphonation gives sulphanilic acid

Friedel - Craft's reaction:
      Friedel Craft's alkylation or acetylation are not possible as salt is formed [due to basic nature of aniline and acidic nature of AlCl3 (lewis acid)] with aniline.

 

Diazonium Salts:
    Compounds with general formula RN2 X (R = aryl, X = Cl-, Br-, HSO4-,BF4-) are called diazomium salts. Primary aliphatic amines form highly unstable alkyldiazonium salts, primary aromatic amines form stable (for a short time) arene diazonium salts (due to resonance) are formed.

Preparation: The conversion of aromatic primary amines into diazonium salts at 0 - 25°C by the reaction of aromatic amine with Nitrous acid (NaNO+ HCl) is called ''diazotisation".


Chemical reactions
Reactions involving displacement of N2:
Replacement by Cl-/ Br- / CN- : 
The reaction in which diazonium group of diazonium salt is replaced by the nucleophiles like Cl-or Br-or CNin presence of Cu+ ion is called "Sandmeyer reaction".

 If the diazonium group of diazonium salt is replaced by the nucleophile like Cl-or Br-or CN-in presence of Cu powder & corresponding halogen acid is called "Gattermann reaction".

Replacement by iodide ion:

Replacement by Fluoride ion:

 

Replacement by H:

Replacement by OH- Group:


Replacement by - NOGroup:


Reactions involving retention of Diazo Group (-N = N-)
Coupling reactions:

  -N2Cgroup is para directing. The reaction in which diazonium salt reacts with aromatic amine or phenol, azocompound having the general formula Ar - N = N - Ar, is called coupling (example of electrophilic substitution).

Cyanides & Isocynides
      
 Alkyl Cyanides are alkyl derivatives of HCN and isocyanides are isomeres of alkyl cyanides. Cyanides are much weaker bases than amines, not soluble in aqueous acids, slightly toxic, have pleasant odours. Isocyanides are highly toxic and have very bad odours, boil at low temperature (than cyanides).
Preparation
From Alkylhalides:
          
Alkylhalides gives alkyl cynaides as major product with ethanolic KCN, but gives alkyl isocyanides as major product with ethanolic AgCN.
C2H5C+ ethanolic KCN  C2HCN + C2H5NC
                                                          (Major)       (Minor)

C2H5C+ ethanolic AgCN  C2H5CN + C2H5NC
                                                         (Minor)        (Major)

From amides & aldoximes:

From 1° amines (Carbylamine reaction):

Chemical Reactions
Oxidation with HgO:

Reduction:

With Grignard reagent:

Cyanides on reaction with RMgX followed by hydrolysis gives Ketones.


Hydrolysis:

Cyanides are used to produce Vinyl Cyanide ( to prepare Nitrile rubbers and synthetic textiles)

Posted Date : 06-08-2021

గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

Special Stories

More

విద్యా ఉద్యోగ సమాచారం

More
 

లేటెస్ట్ నోటిఫికేష‌న్స్‌